The present invention relates to an execution control system for use in a pipeline instruction execution control type information processing device, in which an instruction interval between completion of a certain instruction used in, for example, a debugging process and a readout of a next instruction, is executed by sequencing them.
Sequential control, a basic scheme of execution control, operates in steps of reading out decoding, and executing an instruction, and then, reading out a next instruction.
On the other hand, an execution control using a pipeline system is performed as follows: an instruction which is considered as necessary in the future or an instruction which has been executed recently is stored in an instruction buffer, and the instruction is fetched ahead. The fetched instruction is partially decoded, a portion of processing is performed in parallel to an execution of a current instruction, several instructions are preproccessed in parallel simultaneously. A system for executing instructions between completion of execution of a certain instruction and a readout of a next instruction is usually used in debugging. Therefore, the execution is controlled by an indication from a service processor.
It is assumed in the pipeline instruction execution control type information processor that a program exception occurs during execution of a program. Since, in the information processor of this type, a plurality of instructions are executed in parallel and simultaneously by the pipeline system, it is difficult to identify a program in which such program exception occurred.
Even in a conventional system for sequentially executing the instructions, an instruction execution control portion is indicated through the service processor to execute these instructions sequentially. Hence, the instruction interval is executed sequentially by the information processing device as a whole. Hence when a plurality of programs are being processed by the information processing device, it is impossible to sequentially execute the instruction interval in only a desired portion of a specific program.